Kevin Frick takes a photo with a friend at the Boston Marathon before the explosions.

Dr. Wade Gaasch, a University of Maryland doctor and fire department official who completed the Boston Marathon 20 minutes before the deadly explosions that killed three people, said he was saddened but not surprised by the attack.

Gaasch told 11 News he was about three blocks away when the explosions happened Monday and was not able to provide aid because police were directing the public away from the scene.

"I was turning around to go back, looking down toward the finish line when I saw the plume of smoke go up and heard the explosion shortly thereafter. You could actually feel the shock wave from it," he said, describing panic and then realization. "The bewilderment of everybody just milling around, not knowing what to do, not knowing what happened and not knowing where to go."

Gaasch is a former firefighter and emergency medical technician and also serves as the emergency medical services director for the Baltimore Fire Department. This was his 13th consecutive year running the marathon, and he said he's always felt this was a matter of when an incident like this would happen -- not if.

"As much as they try to prepare for things like this, it's still kind of a relatively uncontrolled setting. It's not like a football game or a baseball game where everyone can be inspected as they walk in the gate," Gaasch said. "That's not the case with a marathon or a triathlon or something like that."

Gaasch, 58, said he was far enough away that he couldn't immediately tell what happened.

"It kind of sounded like a starter cannon that I've had at some races that I do, only much bigger, but within just a matter of seconds I thought, 'No, that's not right,'" Gaasch said. "And probably about 20 seconds later, the second one went off, and immediately, there was no question in my mind."

The explosions at the Boston Marathon happened near a medical tent, where many doctors and aid providers were already stationed. As a doctor, Gaasch said his first instinct was to try to help.

"Even now, I feel like, is there something else I could have done? Obviously, they weren't going to let me in the cordoned-off zone," he said. "But if something like this was going to happen, the fact that it happened right there, from a victim's standpoint, couldn't have been better."

Meanwhile, Kevin Frick, a dean at the Johns Hopkins School of Business, had finished the race and heard about the blasts as he was being evacuated from the subway. He said his first instinct was to text his wife.

"The text message was just, 'Explosion happened, but I'm OK. I'll get back to you later.' But it was just a feeling of helplessness," he told 11 News reporter Kai Reed. "Why were we lucky enough to get through? I'm starting to realize it could have been anytime. Why did it go off just then?"

Frick got home at 1 a.m. Tuesday and said the first thing he did was wake his son up, give him a hug and let him know that he was OK.

Both men talk about their sadness and the images they won't soon forget.

"Everyone who runs the Boston Marathon has worked extremely hard to get there. Their families are there celebrating them," Gaasch said. "It's sad -- I can't think of a better word."

Baltimore will host its annual marathon Oct. 12.

Asked if he could think of any way the city should act or prepare differently than Boston, Gaasch replied, "That's a tough question, and we always think about that. I can tell you Boston did everything I could imagine."

Of the tens of thousands of people running in the Boston Marathon, about 450 of them were from Maryland.